TRAFFIC SIGNALS TRAFFIC SIGNAL COMPONENTS TYPES OF TRAFFIC SIGNAL

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TRAFFIC SIGNALS TRAFFIC SIGNAL COMPONENTS TYPES OF TRAFFIC SIGNAL Powered By Docstoc
					          TRAFFIC SIGNALS                       And Vehicle Detection Systems, either            of vehicles. Pedestrians MUST push the         example by monitoring the arterials during
                                                                                                 pedestrian push button in order to cross       events such as the Rose Bowl, TMC staff
                                                D)      Inductive loops or sensors               either the major or minor streets.             can make adjustments to the signal timing
                                                                     Or                                                                         to facilitate better ingress and egress.
A traffic signal is an electronic device that   E)      Video detection system
assigns right-of-way at an intersection or                                                                                                       Another type of ITS device is a Changeable
street crossing by means of displaying the                                                            TRAFFIC MANAGEMENT                        Message Sign or CMS. They are
standard red, yellow, and green-colored              TYPES OF TRAFFIC SIGNAL                                CENTER                              strategically located along major arterials
indications.    In addition, it also works in              OPERATIONS                                                                           throughout the City. These signs display
                                                                                                 The      City   of   Pasadena’s      Traffic
conjunction with pedestrian displays to                                                                                                         useful information to alert motorists of road
                                                                                                 Management Center (TMC) is a state-of-
assign pedestrian crossing right-of-way.        In the City of Pasadena, traffic signals                                                        conditions ahead or Rose Bowl information
                                                                                                 the art computerized traffic signal control
                                                mainly operate in three modes:                                                                  during event day.
                                                                                                 system. The computer monitors the City’s
           TRAFFIC SIGNAL                                                                        traffic signals 24 - hours a day and city
                                                1.    Fixed-time
            COMPONENTS                          2.    Semi-Actuated
                                                                                                 traffic engineers use this information to
                                                                                                 make signal timing adjustments. All traffic
                                                3.    Actuated
Most traffic signals will have the following                                                     signals are programmed with special
components or parts:                                                                             timing plans to improve traffic flow
                                                Fixed-time mode:      Under this mode,           citywide.
                                                there are no detections for any approach.
                                                The signal continuously cycles regardless        Technological applications in traffic
                                                of actual traffic demand. Pedestrian walk        engineering are referred to as Intelligent
                                                signals are automatic and will cycle             Transportation Systems (ITS). ITS devices
                                                concurrently with the vehicular signal           include Closed Circuit Television (CCTV)
                                                indication.                                      cameras which are used to monitor traffic
                                                                                                 flow along major arterial segments to
                                                 Semi-Actuated mode:        Under        this    ensure that traffic synchronization is
                                                mode, the detection system is present only       working properly.
                                                on a minor cross street. When detection is
                                                activated, the green light on a major street
                                                is interrupted to allow the minor street                                                           Quick Traffic Signal Facts:
                                                traffic and pedestrians to safely enter the
                                                                                                                                                   •   There are 300 signalized intersections
                                                intersection. Pedestrian walk signals for
                                                                                                                                                       in Pasadena.
                                                crossing a minor street are automatic,                                                             •   There are 20 CCTV Traffic Surveillance
                                                while those for crossing a major street are                                                            Cameras.
                                                not. Pedestrians crossing a major street                                                           •   There are 10 Changeable Message
A)     Main display with red, yellow, and       must push the “pedestrian push button” to                                                              Signs.
                                                                                                                                                   •   Three (3) intersections are equipped
       green lights.                            get the walk signal.
B)     Pedestrian crossing lights containing                                                                                                           with Red Light Camera system.
       both the “WALK” and “DON’T WALK”         Actuated mode:            Under this mode,       In addition, the CCTV cameras are
       light indications.                       there are detections for all approaches.         beneficial to handle traffic caused by non-
C)     Traffic signal cabinet containing the    The traffic signal is set to provide the green   recurring events such as accidents,
       traffic signal controller.               light “on-demand” or only in the presence        freeway closures and special events. For
                                                  collisions and the number of observed            A.      There may be excessive delays for
                                                  violations. One of those locations is at         motorists and increased utilization of minor
  TRAFFIC OPERATIONS AT THE                       Marengo Avenue at Union Street (see              streets where new signals are installed.
  PASADENA METRO GOLD LINE                        picture below).                                  Also, motorists may sometimes cut
        STATION AREAS                                                                              through residential neighborhoods to avoid
                                                                                                   a congested signalized location.

                                                                                                   Q.      Along Arroyo Parkway at Del Mar
                                                                                                   and California Boulevards, there are new
                                                                                                   signal displays that show a blinking yellow
                                                                                                   arrow. What does this signal display
                                                                                                   mean?                                           TRAFFIC SIGNALS
                                                                                                   A.       A blinking or flashing yellow arrow
                                                                                                   means that you may proceed to make a
                                                                                                   left-turn with caution, if oncoming traffic
                                                                                                   has cleared the intersection.
As a proponent of multimodal transportation       A high-level security encrypted digital video    Q.      What should motorists do if a traffic
systems, the City of Pasadena is fortunate to     camera system is installed at each               signal is flashing red or is inoperable?
have the Pasadena Metro Gold Line service         approach of the intersection and records
six stops in Pasadena (see above).                those motorists that violate the red light       A.      The California Vehicle Code
                                                  indication. Violations are verified by the       requires drivers to approach the
Most of the Gold Line in Pasadena is
                                                  Pasadena Police Department, and citations        intersection as if it was stop-controlled.
traversing through its own dedicated right-of-
                                                  are sent by mail to the registered owner of      Motorists must make a complete stop, look
way, completely separated from road traffic.
                                                  the vehicle.                                     both ways and proceed through the
At the southerly portion of the line, there are
                                                                                                   intersection when it is safe to do so.
three grade crossings along Del Mar                               F.A.Q.’S
Boulevard,     California   Boulevard,     and                                                     We hope you have found this information
Glenarm Street. In this area, a dedicated                                                          useful. Please contact us if you have any
traffic control system minimizes delay to         Q.     How are traffic signals installed?
                                                                                                   questions or comments.
motorists caused by Metro Gold Line
                                                  A.                            re
                                                         A series of studies a conducted
crossings. Special signal timing plans (with                                                       For more information contact us:
                                                  by Traffic Engineers and these results are
ongoing refinement) mitigate traffic delays as
                                                  measured against guidelines established                      City of Pasadena
commuter traffic interacts with each train                                                              Department of Transportation
                                                  by the State of California, Department of
arrival.                                                                                                 Traffic Engineering Division
                                                  Transportation (Caltrans). These results
                                                  are used to s  how that a traffic signal is         221 East Walnut Street, Suite 210
        RED LIGHT ENFORCEMEN T                    warranted, and then it is placed as a future             Pasadena, CA 91101
                                                  improvement in the City’s Capital                        626.744.TRIP (8747)
Red Light Cameras are located at critical                                                                             Or
                                                  Improvement Program (CIP).
intersections in the City. The locations are
                                                                                                            visit our website at
based on safety needs of the intersection as      Q.       Are there disadvantages            of
shown by a high number of broadside               installing traffic signals?                       http://www.cityofpasadena.net/trans